It is difficult for me to put this in words, but i want a painting game. A game where you can paint everything and use it as some kind of weapon. Maybe also where you can create or manipulate stuff by painting. And where you are totally free to create anything, and not just by painting a few recognizable patterns but are totally free to paint anything you want. Of course this would probably require some sophisticated AI
Another idea is that you are presented with a black and white world, and depending on how you paint it (or not paint it) stuff happens and the world changes as you progress through the game. I only have a fuzzy idea about this, and would like it to be highly unconventional and very stylish game.